1. Field of the Invention
This invention relates in general to certain new and useful improvements in color digitizing scanninq apparatus, and more particularly, to digitizing scanning apparatus for scanning and recording of colored images and which eliminates any light flicker from a light source which illuminates the colored image.
2. Brief Description of the Prior Art
In recent years, there has become an increased interest in utilization of electronic scanning apparatus and particularly, the so-called digitizing scanning apparatus. Apparatus of this type are adapted to scan a document, such as a printed page, and generate electrical signals representative of that material on that printed page. The electrical signals are stored and are capable of being re-accessed for re-creating the original image.
Recently, there have been some attempts to scan and store colored images, as well. One of the principle problems encountered in the scanning of colored images is the fact that the source of light used to illuminate the image has a known flicker rate. As a simple example, fluorescent tubes are effective in illuminating the image to be scanned. Essentially all fluorescent tubes have a known and essentially unremovable flicker rate.
There have been several attempts to eliminate this problem of the flicker of the light source. One of the most prominent attempts has been in the use of a very large ballast, such as a thirty kilohertz ballast. However, it may be appreciated that a ballast of this size and type not only significantly adds to the cost of the apparatus, but it presents several drawbacks, such as heat generation. As a result, means must be provided for eliminating excessive heat build-up.
When scanning a colored document for generating electrical signals representative of the colored image, it is necessary to use filters containing three colors, such as red, blue and green. One attempt to overcome the light flicker problem relied on multiple scanning movements to scan and record a single image including a complete scanning pass with a red filter, a second complete scanning pass with a blue filter, are a third complete scanning pass with a green filter. However, it may be appreciated that this type of system is quite slow in operation since at least three individual scans must be made for each document. Moreover, there is then a need to register each of the three scans.